In general, an ultimate objective of an exhaust gas recirculation (EGR) apparatus mounted on an engine for heavy construction equipment is to control discharge of nitrogen compounds (NOx) by inducing complete combustion inside the engine rather than to achieve high output by using a turbocharger or the like.
FIG. 1 illustrates a configuration view of an exhaust gas recirculation apparatus for heavy construction equipment related to the present disclosure.
As illustrated in FIG. 1, the present disclosure relates to an exhaust gas recirculation apparatus for heavy construction equipment, including: an engine 110; a turbocharger 120 which rotates a turbine 121 by using exhaust gas discharged from the engine 110, and compresses air, which is supplied to the engine 110, by a compressor 123 connected to the turbine 121 through a connecting shaft 122; an intercooler 130 which cools compressed air flowing into the engine 110; a high-pressure EGR line 140 which is provided with a high-pressure EGR cooler 142 and a high-pressure EGR valve 141, and does not pass through the turbocharger 120; a hybrid EGR line 150 which is provided with a hybrid EGR valve 151 and a hybrid EGR cooler 152, and does not pass through the turbine 121 of the turbocharger 120 but passes only through the compressor 123; and a low-pressure EGR line 160 which is provided with a low-pressure EGR valve 161 and a low-pressure EGR cooler 162, and passes through the turbocharger 120.
In the exhaust gas recirculation apparatus for heavy construction equipment, when the high-pressure EGR valve 141 is opened, a part of the exhaust gas discharged from an exhaust manifold 112 of the engine 110 is cooled in the high-pressure EGR cooler 142, and then supplied to an intake manifold 111 of the engine 110 together with fresh gas compressed by the compressor 123, while passing through the high-pressure EGR valve 141 and the intercooler 130, and when the low-pressure EGR valve 160 is opened, a part of the exhaust gas, which is discharged from the exhaust manifold 112 of the engine 110 and passes through the turbine 121 of the turbocharger 120, is induced into the compressor 123 of the turbocharger 120 while passing through the low-pressure EGR valve 141 and the low-pressure EGR cooler 142, compressed by the compressor 123 together with fresh gas flowing in through an air cleaner 170, and then supplied to the intake manifold 111 of the engine 110 while passing through the intercooler 130.
Further, when the hybrid EGR valve 151 is opened, a part of the exhaust gas discharged from the exhaust manifold 112 of the engine 110 is induced into the compressor 123 of the turbocharger 120 while passing through the hybrid EGR valve 151 and the hybrid EGR cooler 152, compressed by the compressor 123 together with fresh gas flowing in through the air cleaner 170, and then supplied to the intake manifold 111 of the engine 110 while passing through the intercooler 130.
Meanwhile, if the exhaust gas recirculation apparatus for heavy construction equipment is configured only with the high-pressure EGR line 140 which does not pass through the turbocharger 120, a process is necessary which allows a control balance between the exhaust gas recirculation apparatus and the turbocharger (T/C) to be maintained.
Further, as illustrated in FIG. 1, when the hybrid EGR line 150 and the low-pressure EGR line 160 are added in addition to the high-pressure EGR line 140, because even the exhaust gas, which is moved to the turbocharger (T/C) and the existing high-pressure EGR line 140, becomes an important factor that needs to be considered to be controlled, a control system is necessary which may maintain a balance between constituent components.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.